Method of illuminating rooms



g- 1938- P. SCHLUMBOHM 2,125,319

HETHOD OF ILLUMIHATIN Filed Aug. 15, 1935 WWW Patented Aug. 2, 1938 UNITED STATES PATENT OFFICE August 14, 1934 I The invention relates to the artificial illumination ofrooms and is aiming at the special task of illuminating a room with artificial daylight of diifused' character. Moreover, any .light of a desired spectral composition may be created for the illumination of rooms by means of the technical rules as disclosed by this invention.

The invention is illustrated by way of example, 4

diagrammatically. partly in section and partly in view in the accompanying drawing. In this drawing a lamp I5 is standing with its base It on the floor 22 of a. room the ceiling of which is indicated by part 2!. The sketch oi! a human figure is to indicate the proportions of the lamp 5 and its level in the room, the ceiling of which is equipped in' a special way. As near to the celling as possible there is a color-filter mirrored reflector 20. The globe I! of the lamp is screened oi! against the eye of the man standing next to to the lamp by the screen II, which is polished inside to work as a reflector. Between the globe i9 and the color-filter mirror 20, a divergent lens i! is provided. Thus the light of the globe l9 is'thrown-as a widely divergent beam against 25 a 'large surface of the color-filter mirror. The lens l8 has two efiects: first, to avoid a strong and disturbing image of the globe IS inthe mirror"; second, to produce a practically equal intensity of light at the whole surface of the mir- 30 ror 20. Projecting the light in a divergent beam against a large surface of the color-filter mirror makes it possible to use very weak filters for the color-filter mirror, thus diminishing the low of light by absorption-to a minimum. There are 35 many ways, known in the art, of producing a divergent beam of light; the technical means of a biconcave lens as illustrated in the drawing, is only one of such means and other means may be applied as well.

40 I am aware of the fact that it has been proposed to illuminate a room with colored light by painting the ceiling with the desired color and by projecting light againsythose painted walls of the ceiling for the purpose of illuminating the i5 room with the light as reflected from the painted ceiling. This old method has the disadvantage that the loss of light by absorption is very great; furthermore, that a painted wall does not constitute a very precise technical means for obtain- 50 ing certain precise color efiects and finally, that painted surfaces are inclined to fade and to change the color. The new technical means as chosen'in this invention are clearly advantageous in all these points. The loss f light by absorp- $6 tion is extremely small, the ter can be made with utmost precision and sucha filter will remain constant in its optical efiect.

A color-filter. mirrored reflector as applied in this invention may be constituted by a plate of tinted glass which is mirrored at the back, or by a. plate of colorless. glass'which is covered at the backwith a tinted layer of colored metal, like copper, or by a laminated glass which is mirrored at the back and which is combined with a tinted transparent organic foil. 10 I do not claim the use of normal colorless mirrors as reflecting surfaces of the ceiling of a room in connection with a lamp which throws light against this mirror atthe ceiling. .The invention is restricted to the use of color-filter mirrors The daylight illumination effect is obtained by using a normal incandescent lamp II with its yellowish light and by using a mirrored plate .glass of bluish tint for the mirrored reflector 20. Following the invention a very l ght bluish tint is chosen and the bluish coloring matter in 80 the glass is of a very small percentage. I found that a suitable daylight glass for the reflector can be made by adding to a standard ground glass composition the small amount of 0.01% or even less of cobalt oxide as coloring matter for obtaining the bluish color. Such a bluish plate glass, mirrored at the back, will have the suitable properties for the purpose set forth.

Having now described my invention and the manner in which it may be performed, which 40 I may be varied within a fair scope, what I claim is:

1. In a room, means for illuminating the room, said means comprising a color-filter mirrored reflector arranged near the ceiling of the room 4 and an artificial source of light provided with means to project a widely divergent beam oi. light against said reflector, the direct light rays from the source'of light being substantially limited to the upper portion of the room, and said reflector covering a sufiicient portion of the ceiling where-' by the reflected light ,substantialiv illuminates the room. 4

2. Means for illuminating a room as recited in claim 1,in which the lightsource is an incan- 4. In a room, means for illuminating the room,

said means comprising a color-filter mirrored reflector on the ceiling of the room and covering substantially the entire ceiling and an artificial source of light provided with means to project a widely divergent beam of light against said reflector, the light rays from the source of light being substantially limited to the upper portion of the room, whereby the room is illuminated by light filtered and reflected by said reflector.

PETER SCI-ILUMBOHM. 

